Energy conservation has lately acquired increasing significance. In conventional internal combustion engines of automotive vehicles an actuator member, commonly the accelerator pedal, is usually rigidly connected to an output control member. In gasoline engines the output control member is as a rule a throttle valve; in Diesel engines it is the control plunger. Owing to this rigid connection there exists a definite relationship between the position of the actuator member and the position of the output control member. This definite relationship is disadvantageous in that the internal combustion engine is driven more or less frequently at unfavorable operating conditions at which it operates at a relatively high specific fuel consumption.
With a view to avoiding this disadvantage German patent specification DE-OS No. 29 26 105 proposes a coupling means of the kind under consideration in which the accelerator pedal is connected to the throttle valve by means of a Bowden wire, the throttle valve being additionally actuated by a servomotor which is controlled by an electronic control unit.
This arrangement is such that with increasing actuation of the accelerator pedal the throttle valve may increasingly be moved to its open position, the position of the accelerator pedal determining the minimum opening of the throttle valve. The servo motor, except when the valve is fully open, may move the valve from any opening to a wider opening which results in slackening of the Bowden cable. This prior art arrangement brings about an initial acceleration of the internal combustion engine in accordance with the position of the throttle valve as set by the accelerator pedal. As soon thereafter as a consumption efficient curve in a torque performance graph stored within the electronic control unit is reached, the throttle valve is automatically opened further by the servomotor in such a manner that the internal combustion engine accelerates further along this chosen consumption efficient curve.
One characteristic of this known device resides in the fact that the electronic control unit cannot move the throttle valve to its closed or slightly open position when the accelerator pedal is positioned at mid-range, for instance. Because of this the operative range of the electronic control unit is limited.